I cover science and public policy, environmental sustainability, media ideology, NGO advocacy and corporate responsibility. I'm executive director of the Genetic Literacy Project (www.GeneticLiteracyProject.org), an independent NGO, and Senior Fellow at the World Food Center's Institute for Food and Agricultural Literacy at the University of California-Davis. I've edited/authored seven books on genetics, chemicals, risk assessment and sustainability, and my favorite, on why I never graduated from college football player (place kicker) to pro athlete: "Taboo: Why Black Athletes Dominate Sports and Why We're Afraid to Talk About It". Previously, I was a producer and executive for 20 yeas at ABC News and NBC News. Motto: Follow the facts, not the ideology. Play hard. Love dogs.

Are GM foods harmful or nutritionally less beneficial when compared to conventional or organic foods? Scientists and regulators almost universally say “no.” That’s why a study published this week claiming that GM corn causes cancer in rats is creating such a furor. What’s the story behind the story? Jon Entine, executive director of the Genetic Literacy Project, reports.

Does Monsanto’s Roundup Ready corn (Europeans call it maize) cause health problems? It’s a reasonable question. It’s been asked and answered, at least to the satisfaction of most researchers.

There have been more than 100 peer-reviewed studies over the years—many by independent, non-industry scientists—that have demonstrated the safety of GM crops and food. This study by a team of French researchers in the journal Food and Chemical Toxicology is the first to seriously challenge the scientific consensus—and its release comes just in time to play a disruptive role in the upcoming California vote on Proposition 37, which would require mandatory labeling of all food products that include any biotech component.

In a nutshell, the team of French researchers claimed to have found that rats fed a high dose lifetime diet of Monsanto’s genetically modified corn or exposed to its top-selling weed killer Roundup suffered tumors and multiple organ damage.

Lead researcher Gilles-Eric Seralini of the University of Caen said they found that rats fed a diet containing NK603—a seed variety made tolerant to the spraying of Roundup—died earlier than those on a standard diet. They reported that 50 percent of males and 70 percent of females died prematurely, compared with only 30 percent and 20 percent in the control group.

Considering these controversial findings—out of synch with all of the published research so far showing GM food and crops to be safe and nutritionally equivalent or even superior (as a result of vitamin enhancement) to conventional and organic foods—it’s no surprise that the story exploded on the web. More than 10,000 articles appeared in a matter of hours.

It was euphorically received by anti-GM campaigners around the world who immediately moved to leverage the conclusions. “Setting aside possible health issues, the pervasive use of herbicide-resistant crops in the US is perpetuating a rapidly escalating arms race with insects and weeds that develop a resistance to the industry’s potent poisons as they become more common,” wroteAviva Shen at Think Progress. The study may also buoy anti-Monsanto food activists who organized 65 protests this past week alone at Monsanto facilities across the country.

The reaction to the report by scientists who are expert in this area has ranged from bewilderment to derision to hints of research malpractice.

“Even though I strongly support labeling, I’m skeptical of this study,” said Marion Nestle, professor in the Department of Nutrition, Food Studies and Public Health at New York University. “It’s weirdly complicated and unclear on key issues: what the controls were fed, relative rates of tumors, why no dose relationship, what the mechanism might be. I can’t think of a biological reason why GMO corn should do this.”

Mark Tester, a research professor for the Australian Centre for Plant Functional Genomics at the University of Adelaide noted that the findings raised the question of why no previous studies have flagged similar concerns. “If the effects are as big as purported, and if the work really is relevant to humans, why aren’t the North Americans dropping like flies? GM has been in the food chain for over a decade over there—and longevity continues to increase inexorably,” he wrote in a comment emailed to Reuters.

As one researcher noted, for nearly 20 years, billions of animals in the European Union and the United States have been fed soy products produced from genetically modified soybean, mainly from Latin America. Yet, no problems have been reported by the hundreds of thousands of farmers, officials and vets.

The London-based Science Media Centre, which assists reporters when major science news breaks, posted an entire page of criticisms from scientists, researchers and professors. David Spiegelhalter of the University of Cambridge writes that the methods, statistics and reporting of results were all below standard. Among the concerns highlighted:

The published does not present all the data. “All data cannot be shown in one report and the most relevant are described here’”—this is a quote from the paper, which means that no reader can evaluate the findings, which mean the data may have been cherry picked

Small sample size. The control group is inadequate to make any deduction. Only 10 rodents some of these develop tumors. Until you know the degree of variation in 90 or 180 (divided into groups of ten) control rodents these results are of no value.

Maize was minimum 11% of the diet—that’s nor a normal diet for rats and invariably distorted the data

In Fig. 2, the bars with a zero appears to be for the non-maize control, yet those bars don’t look significantly different from the bars indicating 11, 22, and 33% of GM maize in the diet. The authors do not appear to have done analysis of their data.

The data from the control group fed non-GM maize is not included in the main figures making it very difficult to interpret the results

No results given for non-gm maize

The same journal published a paper showing no adverse health effects in rats of consuming gm maize (though this is a shorter 90-day study)

Wendy Harwood, senior scientist at the John Innes Centre in Norwich, UK, reviewed the study, concluding: “The findings do not contradict previous findings that genetic modification itself is a neutral technology, with no inherent health or environmental risks. These results cannot be interpreted as showing that GM technology itself is dangerous.”

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Mr. Entine, your link in your article that purports “Over 100 studies showing GMOs are safe” links to one, single abstract (not the whole study), and only to that one study. Care to share the other 99 you are aluding to, if they exist?

There have not been a great number of studies on the safety of GMO foods that go beyond a couple of months. Considering most people will be eating GMO foods for decades, it would make sense to me that there should be more in-depth studies.

Some GMO foods have been genetically altered to biologically create pesticides. I have a hard time believing that those foods wouldn’t have a long-term effect on the people consuming them. I thing Monsanto must agree with me, because they haven’t performed even one single long-term safety study on those types of GMO foods. Or maybe you can provide me a link to the “100s of studies”. HA.

Mr. Marshall, that link goes to a study reviewing hundreds of studies. There have actually been far more studies than that. Just go to PubMed and search “genetically modified food.” http://www.ncbi.nlm.nih.gov/pubmed?term=genetically%20modified%20food GMO crops create natural pesticides, which are in nature. There have been numerous long term studies. None has found any problems to date. To be candid, scientists–government or anti-GM researchers–do not pursue long term studies because you can’t prove a negative. It’s generally a waste of time and money. Scientists from around the world have found that GM foods are biologically equivalent to non-GMO foods. Proteins are proteins. You may have a hard time believing that GM foods are not harmful but you’d feel differently if you understand basic genetics.

John, how can you make these claims? The 100s of studies you reference are primarily industry studies. The future of the human species is at stake and you take this so lightly. In 100 years when we no longer eat genetically modified foods and we look back at the people that did as morons, your name will be proudly displayed as the idiot that told people eating genetically modified foods is OK.

We have had genetically modified foods for more than three thousand years. The future of humankind is not at stake. I don’t want to be rude but that is a fundamentally ignorant statement. No studies–industry or non-industry–have ever found any health problems. People have been consuming GM foods in the US for more than two decades. 70% of processed foods contain GM ingredients. Almost every health measure that we have in the US is trending downward. I’m just stunned at this ignorance. The overwhelming majority of scientists who work in this field or uber-liberals, and they will all tell you that GM foods are safe. Moreover, GM crops are far more sustainable than conventionally grown foods–they consume less pesticides. GM crops and foods should be at the top of any progressives wish list–and they are among the most educated progressives. Just a basic understanding of how GM technology works would dissipate most of the hysteria….unless one is totally closed to empirical evidence.

This current study should underscore the point that a non-industry study is no more or less credible than an industry study. In fact, if you know how the government works, industry studies that are used as part of the GM approval process undergo far more scrutiny than non-industry studies. This French study is proof of the classic adage: garbage in, garbage out. Scientists with no skin in this game–none of the ones I quoted have industry ties–found it literally a piece of cra- . We have literally millions if not billions of data points–the consumption of GM foods over decades in the US and the consumption of GM grains by animals around the world for an equal period of time. There is ZERO evidence of any harm to humans or animals. That’s as controlled a long term experiment as you could hope to have. Drop the hysteria…please. Scientists are not evil people. Empirical data can be manipulated–we see that clearly in this current corrupted study–but scientists are not dumb–scientists can spot these kinds of transparent manipulations.

I’ve written extensively on the labeling debate at GeneticLiteracyProject.org, including a recent story as to why Rachel Carson would have been an avid supporter of GM foods. Check out those articles. We also posted today a great story on the pluses and minuses of labeling that appeared in the Los Angeles Times. The Obama Administration, leading regulators, the American Medical Association and many of the most influential and independent science organizations in the country are against labeling because of its inherent deceptive nature when it comes to labeling a product in which there are no known health issues–as is the case with GM foods. Here’s the link to the LA Times story: http://www.latimes.com/business/la-fi-hiltzik-20120916,0,2211926.column

Proteins are not proteins. They are all different and some can lead to immune system reactions like allergy, autoimmunity or anaphylaxis. Additionally, the relationship between GMO and disease is more than just casual. There is causation as defined by Hill’s Criteria. “The strength of association and consistency between GM foods and disease is confirmed in several animal studies.” http://aaemonline.org/gmopost.html

You are not correct. Proteins ARE just proteins. That’s exactly why any particular protein can lead to an immune system reaction. The point I made is that there is nothing biologically unusual about adding a protein to a crop. Humans have done that for thousands of years. The wheat that we consume today has been developed through biological manipulation–cross breeding–over thousands of years, for example. We’ve used radiation to create mutations that have created new foods–we’ve done this for decades. Each of these processes could introduce new proteins, which may or may not prove allergenic to a tiny subset of the population. The point is that high tech versions of gene manipulation are an extension of an age old process. All foods should be monitored for the potential to create allergens. But the ‘theory’ put out by anti-GM campaigners that we can create super-allergens is just nonsense. Anti-GM campaigners base their opposition on the contention that the very process of creating new GM crops is inherently dangerous–and there is no evidence of that. It displays an ignorance of basic genetics.